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体外预应力钢-混凝土组合梁同时具有预应力钢结构、预应力混凝土结构和非预应力组合梁的特点,这使得影响其长期挠度的因素众多。该文作者推得了综合考虑混凝土板中非预应力纵向钢筋、混凝土收缩、徐变和预应力筋松弛等因素影响的体外预应力钢-混凝土组合梁长期挠度计算模型,并已得到试验结果验证。在此基础上,通过张拉龄期、初始有效预拉力、非预应力纵向钢筋配筋率、混凝土板宽度、钢梁高度、环境年平均相对湿度、混凝土强度等级以及预应力筋种类等因素的不同取值,分析各因素对体外预应力钢-混凝土组合梁长期挠度的影响规律及程度。结果表明:施加体外预应力可以大大减小组合梁附加挠度,当体外预应力抵消全部恒载产生的挠度时,终极跨中附加挠度可以降低28.9%;而且初始有效预拉力值越大,组合梁终极跨中附加挠度越小。该研究成果可为体外预应力钢-混凝土组合梁的设计和挠度控制提供技术依据和参考。
External prestressed steel-concrete composite beams have both the characteristics of prestressed steel structures, prestressed concrete structures and non-prestressed composite beams, which makes many factors affect its long-term deflection. The author deduces the long-term deflection calculation model of externally prestressed steel-concrete composite beams considering the influence of non-prestressed longitudinal reinforcement, concrete shrinkage, creep and prestressing tendon relaxation in concrete slab, and has been verified by the test results. On this basis, through the lacrimation period, the initial effective pre-tensioning, non-prestressed longitudinal reinforcement ratio, concrete slab width, steel beam height, average annual relative humidity, concrete strength grade and the type of prestressing tendon According to different values, the influence of various factors on the long-term deflection of externally prestressed steel-concrete composite beams was analyzed. The results show that additional prestressing can significantly reduce the additional deflection of the composite beam, and when the external prestress counteracts the deflection caused by all dead loads, the ultimate deflection of the final span can be reduced by 28.9%. Moreover, the larger the initial effective pretension value, The ultimate cross in the additional deflection the smaller. The research results can provide technical basis and reference for the design and deflection control of external prestressed steel-concrete composite beams.